1. Field of the Invention
The present embodiments relate to a method of manufacturing a substrate having a thin film transistor (TFT), a TFT manufactured according to the same, a method of manufacturing a flat panel display device, and a flat display device manufactured according to the same, and more particularly, to a method of manufacturing a substrate having a TFT that can be applied to flexible devices having a plastic substrate, a substrate having the TFT manufactured according to the same, a method of manufacturing a flat panel display device, and a flat display device manufactured according to the same.
2. Description of the Related Art
Thin film transistors (TFTs) used in a flat panel display device, such as liquid crystal display (LCD) devices, organic light emitting display (OLED) devices, or inorganic light emitting display devices, are used as a switching device that controls the operation of each pixel, and as a driving device for driving each pixel.
The TFT includes a semiconductor layer, a gate electrode, and source and drain electrodes. The semiconductor layer includes source and drain regions doped at high concentration and a channel region formed between the source and drain regions. The gate electrode is insulated from the semiconductor layer and located in a region corresponding to the channel region. The source and drain electrodes are respectively connected to source and drain regions.
Recently, flat display devices have been required to have the characteristics of slimness and flexibility.
In order to obtain flexibility of a flat display device, attempts have been made using a plastic substrate instead of the conventional glass substrate.
However, in the case of the plastic substrate, an additional barrier layer must be formed, since the plastic substrate is less waterproof and less resistant to oxygen penetration than the glass substrate. The barrier layer is coated on the surface of the plastic substrate to block the penetration of oxygen or moisture through the substrate. The barrier layer is expensive and requires an additional process.
To obtain a flexible flat display device, an organic semiconductor thin film transistor is used instead of a conventional silicon thin film transistor. When the organic semiconductor is used, an inexpensive thin film transistor can be manufactured, since the organic semiconductor can be formed at a low temperature, and can easily be applied to the plastic substrate, which cannot be used at a high temperature.
However, when a TFT is manufactured using the organic semiconductor, and a light emitting device is subsequently formed by a conventional process, the organic semiconductor is easily deformed. Particularly, in the case of the OLED device, forming a pixel electrode connected to the TFT and forming an aperture for a light emitting device on a pixel defining film may both cause problems.
Therefore, to manufacture a flexible flat display device, a new method is needed.